1. Field of the Invention
The present invention concerns a portable electronic device and a method for securing such a device. It is applied, in particular, to microelectronic entities having two interfaces. It concerns the management of the security of portable electronic entities having a plurality of interfaces and, more particularly, to management of the authentication of such an entity.
2. Description of the Related Art
The use of error counters in a secured microcircuit is well known. These error counters are used, for example, in smart cards to monitor the use of a personal identification number (PIN). For example, if an incorrect PIN is received by the card, an error counter is incremented by one. If the next PIN is correct, the error counter is reset to zero. If not, the counter is incremented again. In this way, the error counter retains a count of the number of incorrect PINs received in succession. If the value of this counter reaches a certain limit, subsequent use of the pin, and of the card, is blocked.
Cards are generally supplied with a mechanism that authorizes access, by way of different secret codes, to unblock a blocked card. These secret codes are normally held by the provider of the card, for example a bank. Thus the card holder is obliged to turn to the supplier of the card or a similar authority to unblock their card.
There is known the document FR 2 786 006, which describes an anti-fraud device for an integrated circuit card including a data memory and a counter. The counter counts, on the one hand, a number of occurrences of events that have occurred in the device and is, on the other hand, liable to reach a threshold value. An indicator element goes from a first state to a second state when the counter has reached the threshold value and blocks the operation of the card.
The drawback of these procedures is particularly clear in the case of cards with two interfaces, one requiring contact and the other contactless. A hacker could use the contactless interface to block the card without the cardholder being made aware of this, for example, by sending a series of authentication requests with incorrect authentication codes. Such an attack effected on a large scale could cause considerable damage to the cardholders and to the card provider obliged to intervene to unblock the cards blocked in this way.